Smartphone In Another World

After being hit by a truck in his previous world, our MC awakens in a fantasy world as the son of a small shop owner. Because his parents died, he had to discontinue his education for a year or two to handle their shop while waiting for his big sister's who's only have a year before she graduated. A system appears and assigns him his first task: [Sell 10 smartphones within a week.] "First and foremost, how am I going to market this? Before I died, I was just a regular high school student." "That is your problem, host." . . . Witness how an unnecessary character like him would become the protagonist of his own story.